Tinnitus treatment system and method

ABSTRACT

A tinnitus masking system for use by a person having tinnitus. The system comprises a sound delivery system having left and right ear-level audio delivery devices and is configured to deliver a masking sound to the person via the audio delivery devices such that the masking sound appears to originate from a virtual sound source location that substantially corresponds to the spatial location in 3D auditory space of the source of the tinnitus as perceived by the person. The masking sound being represented by left and right audio signals that are converted to audible sound by the respective audio delivery devices.

FIELD OF THE INVENTION

The present invention relates to the treatment of tinnitus. Inparticular, although not exclusively, the present invention is atinnitus treatment system and method that may be employed by tinnitussufferers to provide short-term and/or long-term relief.

BACKGROUND TO THE INVENTION

Tinnitus is the perception of sound in the absence of a correspondingexternal source. It can be perceived in one or both ears, or in thehead, or outside the head. It is usually described as a ringing noise,but can also be in other forms such as hissing, buzzing, or roaringsounds. Tinnitus can be intermittent or it can be continuous and in suchcases can be a cause of great distress to the sufferer.

Tinnitus is not a disease but a symptom resulting from a range ofpossible underlying causes including, for example, ear infections,foreign objects or wax in the ear, nose allergies, noise-related trauma,side effect of medication or other unexplained causes. Currently, thereis no surgical cure for tinnitus. However, temporary relief forsufferers can be provided by external sound devices, for example maskinginstruments, as tinnitus sufferers often indicate that their tinnitus isless audible in the presence of sounds.

Typically, masking instruments use a noise generator to deliver amasking sound to the patient in order to mask the tinnitus. The maskinginstruments are often customised in that the frequency and intensity ofthe masking sound is often matched to the frequency and intensity of thetinnitus as perceived by the individual patient, and which can beassessed by an audiologist using various tests. Masking can be providedthrough ear-level or non-ear level sound generation devices including,for example, table top generators, bedside maskers, personal soundsystems, standalone ear-level “maskers” for patients with normalhearing, and combination devices such as maskers integrated with hearingaids for the hearing impaired.

Another approach to tinnitus management, is the recent trend towardusing Tinnitus Retraining Therapy (TRT). TRT is a specific clinicalmethod based on a neurophysiological model of tinnitus. The method isaimed at habituation of reactions evoked by tinnitus, and subsequentlyhabituation of the tinnitus perception. Typically, the therapy involvescounseling, aimed at reclassification of tinnitus to a category of aneutral signal, and sound therapy, aimed at weakening tinnitus-relatedneuronal activity. Effectively the TRT method is trying to retrain thepatient's brain so that they treat their tinnitus similar to naturalsounds that they can accommodate.

It is an object of the present invention to provide an improved tinnitustreatment system and method, or to at least provide the public with auseful choice.

SUMMARY OF THE INVENTION

In a first aspect, the present invention broadly consists in a method ofmasking a person's tinnitus comprising: delivering a masking sound tothe person via left and right ear-level audio delivery devices such thatthe masking sound appears to originate from a virtual sound sourcelocation that substantially corresponds to the spatial location in 3Dauditory space of the source of the tinnitus as perceived by the person

In a second aspect, the present invention broadly consists in a tinnitusmasking system for use by a person suffering from tinnitus comprising: asound delivery system having left and right ear-level audio deliverydevices, the sound delivery system being configured to deliver a maskingsound to the person via the audio delivery devices such that the maskingsound appears to originate from a virtual sound source location thatsubstantially corresponds to the spatial location in 3D auditory spaceof the source of the tinnitus as perceived by the person, the maskingsound being represented by left and right audio signals that areconverted to audible sound by the respective audio delivery devices.

Preferably, the ear-level audio delivery devices are headphones,earphones, hearing aids or the like.

Preferably, the sound delivery system further comprises an audiocontroller that is operable to control or trigger synchronized deliveryof the left and right audio signals to the respective audio deliverydevices.

Preferably, the masking sound is provided in the form of a digital audiofile that is stored in memory in the audio controller for playback.Alternatively, the left and right audio signals of the masking sound aregenerated in real-time by a sound processor of the audio controller.

In one form, the audio controller is partially or completely integratedor onboard one or both of the audio delivery devices. In another form,the audio controller may be a separate external device that sends theleft and right audio signals to the audio delivery devices via a wiredconnection or wireless communication.

In a third aspect, the present invention broadly consists in a method ofdetermining a spatial property of tinnitus as perceived by a personcomprising the steps of: sequentially presenting test sounds to theperson from a series of virtual sound source locations in 3D auditoryspace; and receiving feedback from the person as to virtual sound sourcelocation that most closely corresponds to the spatial location in 3Dauditory space of the source of the tinnitus as perceived by the person.

In a fourth aspect, the present invention broadly consists in a systemfor determining a spatial property of tinnitus as perceived by a personcomprising: a sound generation system that is operable to present testsounds to the person from a series of virtual sound source locations in3D auditory space; and a feedback system that is arranged to receiveperson feedback indicative of the virtual sound source location thatmost closely corresponds to the spatial location in 3D auditory space ofthe source of the tinnitus as perceived by the person and output spatialinformation indicative of the spatial location of the source of thetinnitus based on the person's feedback.

In one form, the sound generation system is configured to sequentiallypresent test sound to the person from a range of different virtual soundsource locations. In another form, the sound generation system is useroperable to present the test sounds from user selected virtual soundsource locations.

Preferably, the test sound has one or more sound attributes thatsubstantially correspond or match one or more of the perceived soundattributes of the person's tinnitus. By way of example, the soundattributes may comprise any one or more of the following: pitch,frequency, bandwidth, temporal properties, intensity, loudness, or soundtype.

Preferably, the test sounds are presented sequentially at differentazimuth and elevation angles within respective predetermined azimuth andelevation ranges relative to a reference point in a 3D auditory spacereference frame. Preferably, the reference point is the center of themidline axis between the ears.

Preferably, the azimuth is the angle of a vector about the referencepoint in a reference plane extending horizontally through the center ofthe person's head, and the elevation is the angle of the vector above orbelow the reference plane.

Preferably, the test sounds are continuously swept through the entireazimuth and elevation ranges. Alternatively, the test sounds may besequentially presented at a series of discrete azimuth and elevationangles.

In a fifth aspect, the present invention broadly consists in a method ofgenerating a spatial masking sound for a person having tinnituscomprising the steps of: receiving a masking sound, receiving spatialinformation indicative of the spatial location in 3D auditory space ofthe source of the tinnitus as perceived by the person; modifying thespatial playback properties of the masking sound based on the spatialinformation so as to generate a spatial masking sound that may be playedto the person via left and right ear-level audio delivery devices suchthat the sound appears to originate from a virtual sound source locationthat substantially corresponds to the spatial location of the tinnitusas perceived by the person.

In a sixth aspect, the present invention broadly consists in a spatialmasking sound generation system for a person having tinnitus comprising:a sound processor that is arranged to receive a masking sound andspatial information indicative of the spatial location in 3D auditoryspace of the source of the tinnitus as perceived by the person, andwhich is further configured to modify the spatial playback properties ofthe masking sound based on the spatial information so as to generate aspatial masking sound that may be played to a person via left and rightear-level audio delivery devices such that the sound appears tooriginate from a virtual sound source location that substantiallycorresponds to the spatial location of the source of the tinnitus asperceived by the person.

Preferably, the spatial masking sound is represented by left and rightaudio signals. More preferably, the spatial masking sound is stored orcompiled into a digital audio file in any suitable audio format or othersound recording format, whether digital or analogue.

Preferably, the audio delivery devices are headphones, earphones,hearing aids, or any other suitable audio transducers for converting theaudio signals into audible sound.

Preferably, the masking sound has sound attributes that are configuredto substantially correspond to one or more of the sound attributes ofthe tinnitus as perceived by the person. By way of example, the soundattributes may comprise any one or more of the following: pitch,frequency, bandwidth, temporal properties, intensity, loudness, or soundtype.

In a seventh aspect, the present invention broadly consists in atinnitus masking audio system for a person having tinnitus comprising:left and right ear-level audio delivery devices that convert respectiveleft and right audio input signals into audible sound, the left andright audio input signals representing a masking sound having a virtualsound source location in 3D auditory space that substantiallycorresponds to the spatial location of the source of the tinnitus asperceived by the person; and an audio controller that is operable tocoordinate synchronized playback of the left and right audio signalsover their respective audio delivery devices.

Preferably, the ear-level audio delivery devices are headphones,earphones, hearing aids or the like.

Preferably, the masking sound is provided in the form of a digital audiofile that is stored in memory in the audio controller for playback.Alternatively, the left and right audio signals of the masking sound aregenerated in real-time by a sound processor of the audio controller.

In one form, the audio controller is partially or completely integratedor onboard one or both of the audio delivery devices. In another form,the audio controller may be a separate external device that sends theleft and right audio signals to the audio delivery devices via a wiredconnection or wireless communication.

In an eighth aspect, the present invention broadly consists in a methodof generating a personalised spatial masking sound for a person havingtinnitus comprising:

-   -   assessing one or more sound attributes of the tinnitus as        perceived by the person;    -   generating a masking sound having one or more sound attributes        that substantially correspond to the perceived sound attributes        of the person's tinnitus;    -   assessing the location of the tinnitus sound source in 3D        auditory space as perceived by the person; and    -   modifying the spatial properties of the masking sound based on        the assessed tinnitus sound source location so as to generate a        spatial masking sound that may be played to the person via left        and right ear-level audio delivery devices such that the sound        appears to originate from a virtual sound source location that        substantially corresponds to the spatial location of the source        of the tinnitus as perceived by the person.

Preferably, the step of assessing one or more sound attributes of thetinnitus as perceived by the person comprises operating an assessmentsystem to generate test sounds having configurable sound attributes forplayback to the person, the assessment system being controlled by anoperable graphical user interface. More preferably, this step furthercomprises receiving the person's feedback on the test sound that mostclosely corresponds to their perceived tinnitus for each sound attributebeing assessed.

Additionally, or alternatively, the step of assessing one or more soundattributes of the tinnitus as perceived by the person comprises testingany one or more of the following: pitch-matching, loudness-matching,tinnitus specific measures, minimum masking level, residual inhibition,loudness growth and discomfort.

Preferably, the method further comprises the step of assessing theintensity of the tinnitus as perceived by the person at the location ofthe tinnitus sound source in 3D auditory space and further modifying theintensity of the masking sound based on the assessed intensity.

By way of example, the sound attributes may comprise any one or more ofthe following: pitch, frequency, bandwidth, temporal properties,intensity, loudness, or sound type.

Preferably, assessing the location of the tinnitus sound source in 3Dauditory space as perceived by the person comprises sequentiallypresenting test sounds to the person from a range of virtual soundsource locations in 3D auditory space; receiving feedback from theperson as to virtual sound source location that most closely correspondsto the spatial location in 3D auditory space of the source of thetinnitus as perceived by the person. More preferably, the test sound isthe masking sound.

Preferably, modifying the spatial properties of the masking soundcomprises employing sound localization processing techniques andalgorithms based any one or more of the following: ITD, ILD, and HRTFs.

The phrase “ear-level audio delivery device” as used in thisspecification and claims is intended to cover any type of audio deliverydevice that can be worn or located on, over or in a person's ear,whether a standalone audio component or integrated with anotherelectronic device or system, and which can be driven to produce audiblesound, including, by way of example only and not limited to, headphones,ear buds, and hearing aids.

The phrase “3D auditory space” as used in the specification and claimsis intended to mean, unless the context suggests otherwise, the volumeof space, whether external to a person or internal, from which actual orperceived sounds are determined as originating from according to thesound localisation processing of the person's brain.

The phrase “masking sound” as used in the specification and claims isintended to mean, unless the context suggests otherwise, any type ofsound that can be used to mask (wholly or partially), cover ordesensitize tinnitus as perceived by a person with the objective ofrelieving and/or desensitizing the person from the tinnitus sound overtime and including for example, but not limited to, music, soundeffects, background noise, white or broadband noise, or any combinationof such sounds or other sounds suitable for this purpose.

The term “comprising” as used in this specification and claims means“consisting at least in part of”. When interpreting each statement inthis specification and claims that includes the term “comprising”,features other than that or those prefaced by the term may also bepresent. Related terms such as “comprise” and “comprises” are to beinterpreted in the same manner.

As used herein the term “and/or” means “and” or “or”, or both.

As used herein “(s)” following a noun means the plural and/or singularforms of the noun.

The invention consists in the foregoing and also envisages constructionsof which the following gives examples only.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will be described by way ofexample only and with reference to the drawings, in which:

FIG. 1 is a flow diagram showing an overview of the steps in a methodfor generating a spatial masking sound for a patient suffering tinnitusin accordance with an embodiment of the invention;

FIG. 2 is a flow diagram showing a more detailed breakdown of the stepsin FIG. 1 in accordance with an embodiment of the invention;

FIG. 3 shows a screen shot of the graphical user interface of anaudiometer assessment interface of a tinnitus diagnosis system for usein calibration in accordance with an embodiment of the invention;

FIG. 4 shows a screen shot of the graphical user interface of atone/bandnoise pitch match function interface of the tinnitus diagnosissystem in accordance with an embodiment of the invention;

FIG. 5 shows a screen shot of the graphical user interface of a volumefunction interface of the tinnitus diagnosis system in accordance withan embodiment of the invention;

FIG. 6 shows a screen shot of the graphical user interface of a firsttinnitus sound-match function interface of the tinnitus diagnosis systemin accordance with an embodiment of the invention;

FIG. 7 shows a screen shot of the graphical user interface of a findsound search feature of a second tinnitus sound-match function interfaceof the tinnitus diagnosis system in accordance with an embodiment of theinvention;

FIG. 8 shows a screen shot of the graphical user interface of a formatsound search feature of the second tinnitus sound-match functioninterface of the tinnitus diagnosis system in accordance with anembodiment of the invention;

FIG. 9 shows a screen shot of the graphical user interface of a soundplayer feature of the second tinnitus sound-match function interface ofthe tinnitus diagnosis system in accordance with an embodiment of theinvention;

FIG. 10A is a schematic representation of the angular data used tocharacterise the spatial characteristics of the tinnitus sound source asperceived by the patient;

FIG. 10B is a midline cross-sectional top plan view of a patient's headand showing the X and Y axes of a 3D auditory space reference frame;

FIG. 10C is a midline cross-sectional elevation view of the patient'shead of FIG. 10B and shows the X and Z axes of the 3D auditory spacereference frame;

FIG. 11 shows a screen shot of the graphical user interface of a 3Dspatial location function interface of the tinnitus diagnosis system inaccordance with an embodiment of the invention;

FIG. 12 shows a screen shot of the graphical user interface of atinnitus intensity function interface of the tinnitus diagnosis systemin accordance with an embodiment of the invention;

FIG. 13A shows a diagram of a configurable ramping architecture formodulating the intensity of the spatial masking sound in accordance withan embodiment of the invention;

FIG. 13B shows an example of a saw-tooth ramping profile for modulatingthe intensity of the spatial masking sound in accordance with anembodiment of the invention;

FIG. 14 is a schematic block diagram of a sound processor system forgenerating a spatial masking sound using virtual acoustic spacetechniques in accordance with an embodiment of the invention;

FIG. 15a is a schematic block diagram showing the main modules of atinnitus treatment system having a first form of hearing aid, having astored spatial masking signal, that is controlled by a remote control inaccordance with an embodiment of the invention;

FIG. 15b is a schematic block diagram showing the main modules of atinnitus treatment system having a second form of hearing aid thatgenerates a spatial masking signal and that is controlled by a remotecontrol in accordance with an embodiment of the invention;

FIG. 16 is a schematic diagram showing the hardware devices of atinnitus treatment system employing synchronised left and right hearingaids controlled by a remote control in accordance with FIGS. 15A and15B;

FIG. 17 is a schematic block diagram showing the main modules of atinnitus treatment system having a hearing aid that is controlled by anexternal audio control device that is configured to generate the spatialmasking signal for the hearing aid;

FIG. 18 is a schematic diagram showing examples of various hardwaredevices that can be employed to implement the tinnitus treatment systemshown in FIG. 17, and in particular employing synchronised left andright hearing aids that can be driven by a range of different audiocontrol devices;

FIG. 19 is a schematic diagram showing the hardware devices that can beemployed to implement the tinnitus treatment system shown in FIG. 17,and in particular employing left and right hearing aids that aresynchronously driven by an external audio control device; and

FIG. 20 shows a schematic diagram of hardware implementation of tinnitustreatment system of another embodiment of the invention that employsleft and right stereo headphones that may be driven by various audiocontrol devices.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 1. Overview of TinnitusTreatment Method and System

The invention relates to a tinnitus treatment system and method that isbased on masking the tinnitus and/or desensitising the patient to thetinnitus. It has been identified that some of the distress associatedwith tinnitus is related to a violation of tinnitus perception fromnormal Auditory Scene Analysis (ASA). In particular, it has beenidentified that neural activity forming tinnitus is sufficientlydifferent from normal sound activity that when formed into a whole imageit conflicts with memory of true sounds. In other words, tinnitus doesnot localise to an external source. An inability to localise a soundsource is “unnatural” and a violation of the fundamental perceptualprocess. Additionally, it has been identified that it is a lack of acontext, or a lack of behaviourally relevant meaning, that force thebrain too repeatedly or strongly attend to the tinnitus signal. Forexample, the sound of rain in the background is easily habituated to.The sound is associated with a visual and tactile perception orperceptual memory of rain as well. The context of the sound isunderstood so it can be processed and dismissed as unworthy of furtherattention. However, there is no such understanding of the tinnitussignal, which does not correspond to a true auditory object.

In some embodiments, the tinnitus treatment and system employscustomised informational masking and desensitisation. Informationalmasking acts at a level of cognition and limits the brains capacity toprocess tinnitus, rather than “drowning it out”, which is what sometraditional white noise (energetic) maskers attempt.

The tinnitus treatment system and method presents a masking sound to thepatient from a virtual sound source location in 3D auditory space thatsubstantially corresponds to the spatial location of the source of thetinnitus as perceived by the patient. In some embodiments, the spatial3D masking sound may also comprise other informational masking features,such as spectral, temporal, and/or intensity sound attributes that arematched to substantially correspond to the tinnitus sound as perceivedby the patient. The system and method aims to enhance tinnitus maskingby spatially overlapping the perceived tinnitus location and the spatialrepresentation (or the virtual sound source location) of the maskingsound.

As will be described in further detail later, the tinnitus treatmentsystem and method employs virtual acoustic technology, such as a VirtualAcoustic Space (VAS) techniques or virtual surround sound processing, topresent or deliver the masking sound to the patient so as to beperceived to originate or emanate from a predetermined direction and/orlocation in 3D auditory space, whether in the patient's head or externalto the patient's head. Typically, the virtual acoustic technology candeliver a spatial masking sound via a pair of stereo (left and right)audio delivery devices such as, but not limited to, ear-level devicessuch as headphones, earplugs or hearing aids that are worn by thepatient.

Referring to FIG. 1, an overview of an embodiment of the tinnitustreatment method 10 is shown. A preferred order of steps is shown by wayof example only, but it will be appreciated that the order may bealtered or varied in alternative forms of the treatment method.Additionally, some steps or stages may be omitted in other forms of thetreatment method.

The first step 12 involves diagnosing the patient's tinnituscharacteristics, as the spatial masking sound is customised for eachpatient. In this embodiment, the tinnitus diagnosis step 12 comprisesfive main stages. Firstly, a sound behavioural calibration diagnosis 62is conducted to determine the patient's individual absolute hearingthresholds (audiogram) and uncomfortable loudness levels. Secondly,tinnitus sound attributes 14 are assessed. The tinnitus sound attributesassessed for the patient may comprise any one or more of the following:perceived sound characteristics (e,g, sound type, such as but notlimited to pure tone, noise, environmental sounds, or any other sounds),bandwidth, temporal properties, loudness (intensity), and pitch. Suchsound attributes or features can be assessed by an audiologist orclinician using various audio tests as will be explained in detaillater. While not essential, it is desirable to assess the patient'sperceived sound attributes of their tinnitus as in some embodiments themasking sound may be configured to match one or more of the soundattributes of the perceived tinnitus. For example, in the third stage, atinnitus synthetic sound 15 matching one or more of the assessed soundattributes may be generated for use in the next assessment stages. Thiswill not necessarily always be the case as in some embodimentsunmodified masking sounds may be delivered to the patient, with the onlycharacteristics overlapping being the spatial characteristics asexplained next.

The fourth stage of the tinnitus diagnosis stage 12 involves assessingthe spatial location 16 in 3D auditory space of the sound sourcelocation of the tinnitus as perceived by the patient. By way of example,the patient may perceive the tinnitus sound as originating from one ear,both ears, within their head or external to their head. Tests can becarried out by audiologist or clinician to determine the sound sourcelocation of the tinnitus as perceived by the patient, as will beexplained in more detail later. The spatial location of the perceivedtinnitus source may be represented in various forms in 3D auditoryspace, but in this embodiment the spatial location of the tinnitus isrepresented by a 3D direction vector that represents the direction fromwhich the patient perceives their tinnitus as originating from relativeto a reference point, such as the centre of their head or any otherdesired reference. In alternative forms, the 3D spatial locationinformation may comprise both a 3D direction vector in 3D auditory spacealong with associated magnitude information representing the distancebetween the perceived tinnitus sound source location and the referencepoint. In some cases a predetermined distance to the perceived tinnitussource from the reference point (e.g. center of patient's head) will beassumed for the patient. This predetermined distance may be based on thesound localisation techniques or algorithms used.

The fifth stage of the tinnitus diagnosis stage 12 involves assessingthe tinnitus intensity 17 in the spatial location in 3D auditory space.Tests can be carried out by audiologist or clinician to determine theintensity of the tinnitus as perceived by the patient as will beexplained in detail later.

The tinnitus sound attribute information, spatial information, andtinnitus intensity information determined during the tinnitus diagnosisstage 12 is used as input for the following masking sound parametersetting steps 18 and 20. Firstly, a masking sound is selected and itssound parameters personalised 18 in view of the patient's tinnitusdiagnosis results. The masking sound selected may, for example, be anysound recording or noise, such as music, white noise, environmentalsounds, natural sounds, sound effects, or the like. One or more of thesound attributes for the masking sound may be configured to match thecorresponding parameters of the tinnitus sound as perceived by thepatient in the diagnosis step 14. Alternatively, the masking soundselected may be the synthetic sound generated at 15 in the tinnitusdiagnosis step 14.

Various optional sound processing parameters 20 may then be configured,such as the masking sound play time, sound diffuse-field, and anydesired playback intensity variation, such as ramping.

Once the desired masking sound parameters are set, the selected maskingsound is signal processed at step 22 using virtual acoustic technologyto generate a spatial masking sound that appears to originate in 3Dauditory space from the same spatial location as the patient's perceivedtinnitus source location. Additionally, sound processing may be employedto modify one or more of the masking sound attributes to matchcorresponding tinnitus sound attributes, depending on the desiredpersonalisation settings from step 18.

The spatial masking sound output from step 22 may be in any suitableform for storage and playback, including any analogue storage medium ora digital sound file. In some embodiments, the spatial masking soundwill be represented by a stereo audio signal and may be provided invarious audio formats, whether analogue or digital, and including forexample way or mp3 file formats. It will also be appreciated that thespatial masking sound may be stored on any suitable medium, whetheranalogue or digital, including on magnetic tapes, optical storagemediums such as CDs or DVDs, or readable memory devices, such as harddrives, memory sticks, whether standalone or part of another media,communication or entertainment device. As will be explained in moredetail later, in preferred embodiments the spatial masking soundgeneration method is primarily employed for generating a masking soundfor playback over hearing aids or headphones worn by the patient. In thecontext of hearing aids, these may have an onboard sound storage and/orgeneration system or may communicate with an external sound storageand/or generation system or device. In embodiments in which the soundgeneration system is onboard the audio delivery devices (e.g. hearingaids) or audio controller, the spatial masking sound output format maybe configured to suit the audio delivery device input signalrequirements.

The final step 24 in the treatment method is the playback of the spatialmasking sound to the patient via a sound delivery system. The sounddelivery system may be operated to play the spatial masking sound to thepatient in accordance with a treatment plan. For example, the patientmay be instructed to play the spatial masking sound at particular timesduring the day or when the tinnitus is most distressing and there may becustomised treatment plans developed for each patient depending on theirrequirements and tinnitus distress profile.

In some embodiments, the spatial masking sound is provided in the formof a stereo audio signal that can be delivered or presented to thepatient via left and right audio delivery devices, such as headphones orhearing aids at the ear level.

The stereo audio signal may be delivered to the audio delivery devicesvia any suitable type of audio control device having sound processingand playback capabilities, including for example a personal computer,PDA, cell phone, or portable audio player (e.g. iPod or mp3 player).Alternatively, the audio delivery devices and audio control device thatstores and controls playback of the spatial masking system may be astandalone integrated treatment device or the audio control device maybe integrated into hearing aids or the like.

2. An Example Embodiment of the Tinnitus Treatment Method and System

Referring to FIG. 2, an example embodiment of the tinnitus treatmentmethod will be explained in more detail with reference to the overviewpreviously provided.

Assessment Tools for Tinnitus Diagnosis

The following tinnitus diagnosis 12 assessments in the treatment methodmay be performed using conventional audiology assessment techniques andsystems for generating a profile of the sound attributes of anindividual's tinnitus and conventional methods of storing or recordingsuch information, whether electronically or otherwise. Additionally oralternatively, one or more of the tinnitus diagnosis assessments may beperformed using a customised electronic tinnitus diagnosis system in theform of software running on a host computer system, which may be aPersonal Computer having a processor, memory, data storage, userinterface, display, and audio output interface for driving speakers,headphones, hearing aids or other connectable audio delivery devices fordelivering test sounds generated by the assessment interfaces to thepatient being assessed.

As will be explained further by way of example below, the tinnitusdiagnosis system software may comprise one or more assessment interfacesor functions to assist the audiologist or clinician in profiling apatient's subjective tinnitus experience in terms of informationrelating to any of the sound attributes 14, 3D spatial location 16, andtinnitus intensity 17. Each of the assessment interfaces comprises anoperable graphical user interface (GUI) that may be operated by theclinician and/or patient for assessing one or more sound attributes ofthe patient's tinnitus. The workflow of some of the assessmentinterfaces may be automated or semi-automated, or alternatively undercomplete control of the operator. The assessment information obtained bythe use of each assessment interface may be stored electronically into acomputer file or files that contain the information representing thepatient's subjective tinnitus characterisation. The various assessmentinterfaces may interact with each other, such that assessmentinformation from one interface is fed into one or more of the otherinterfaces. Optionally, the order of operation of the various interfacesmay also be controlled, such that the tinnitus assessment for eachpatient follows a step-by-step protocol to accurately characterise thepatient's tinnitus. The system may be operated by a clinician with thepatient wearing the audio delivery devices for the test sounds, or mayalternatively be operated by the patient as a self-assessment tool. Aswill be described with reference to FIGS. 3-9, 11 and 12, the overallGUI for the tinnitus diagnosis system may provide each assessmentinterface in a separate accessible tab, which when selected displays theoperable GUI for that assessment interface.

By way of example, in one embodiment the tinnitus diagnosis system thesound format used may be 16-bit with a 44100 sampling rate. Monauralsound may be used to generate the stereo spatial sound. The system maysupport any sound format, including but not limited to the followingformats: .wav, .mp3, .wma, .pcm.

Calibration

Firstly, a patient calibration assessment 62 may be carried out in theform of a behavioural calibration to determine the patient's absolutehearing thresholds and uncomfortable loudness levels (audiogram). Thiscalibration assessment will be conducted using the audio deliverydevices that will be worn by the patient, for example headphones orhearing aids. Such information may be determined from a patient'sclinical audiogram in some embodiments. In some embodiments, thecalibration of absolute hearing thresholds will be applied to compensatehearing at further stages and therefore the further loudness will becontrolled with sound level (dB SL) upon the thresholds.

Referring to FIG. 3, in one embodiment of the method the calibrationassessment may be performed using the audiometer assessment interface150 of the tinnitus diagnosis system. In operation, the audiometerassessment interface provides a measurement tool for hearing thresholdsfor a range of frequencies. By way of example, the measurablefrequencies may be 125 Hz, 250 Hz, 500 Hz, 750 Hz, 1000 Hz, 1500 Hz,2000 Hz, 3000 Hz, 4000 Hz, 5000 Hz, 6000 Hz, 7000 Hz, 8000 Hz, 9000 Hz,10000 Hz, 11000 Hz, 12000 Hz, 13000 Hz, 14000 Hz, 15000 Hz and 16000 Hz,although it will be appreciated that these frequencies may be altered asdesired.

For a new test, the filename for storing the audiogram information maybe entered into the filename box 153. Then, the main control panel 154may be operated to sequentially generate test sounds at a desiredfrequency and gain for either the left or right. The initiate button 155initiates the playback of the selected test sound to the patient, andthe store button 156 saves the threshold result for that test soundfrequency upon the patient's feedback. After each frequency is testedand stored, the audiogram results are plotted in the graphical display157. The save button 158 may be operated to store all threshold resultsinto the desired file entered into 153.

Alternatively, a previous audiogram performed by the patient on thesystem may be loaded by entering the relevant filename into box 153 andthen operating the OK button 159 to load the previous results, which maythen be updated for all or a selection of frequencies.

Tinnitus Sound Attributes

The treatment method then involves determining the patient's perceivedtinnitus sound attributes 14, i.e. characterising the patient'stinnitus. In this example, the bandwidth, temporal properties, loudness,and pitch characteristics of the tinnitus as perceived by the patientare tested and recorded by an audiologist or clinician. As is known tothose skilled in audiology, such tests typically present a series ofsounds with varying attributes and seeking the patient's feedback inrelation to the attributes that most closely match the sound attributesof the tinnitus as they perceive it. By way of example, such audiologisttechniques that may be employed include pitch-matching andloudness-matching. Tinnitus specific measures to see how the patient'stinnitus compares with other environmental sounds may also be undertakento find a tinnitus sound match.

Referring to FIG. 4, in one embodiment of the method the pitch matchingassessment may be performed using the tone/bandnoise pitch matchfunction interface 160 of the tinnitus diagnosis system. The functionuses tonal or bandnoise stimuli with a 2AFC (2-alternativeforced-choice) method to determine tinnitus pitch-match. It allows formodification of various parameters such as bandwidth and centerfrequency to promote a close match to the tinnitus percept. Test earselection panel 163 may be operated to select either the left, right orboth ears to test. The stimuli selection panel 164 may be operated toselect the type of stimulus for the test sound playback, for exampleuniform white (white noise) or sine (tonal). The intensity slider scale165 may be adjusted to set the desired intensity of the test sound.Operation of the start button 166 initiates the test sounds for playbackto the patient for their feedback on pitch-matching to their tinnitus.Depending on their feedback, the center frequency 167 and/or bandwidth168 of the stimuli may be adjusted to generate new test sounds to enablea closer pitch-match. The process is repeated until the closestpitch-match is obtained. The sound spectrum of the test sounds isdisplayed in the spectrum graphical display 169. The save button 170 maybe operated to store the pitch-match results into a new or selected datafile. A further stop button 171 is also provided for halting theinterface. The interface compensates for any hearing loss as determinedin the audiometer assessment interface 150.

Referring to FIG. 5, in one embodiment of the method the loudnessmatching assessment may be performed using the volume function interface180 of the tinnitus diagnosis system. Upon initialisation, the interfaceautomatically plays a noise to the patient. The generated noise iscompensated for any hearing loss based on the audiometer assessmentinterface 150 results. The user may then operate the main control panel182 to adjust the volume slider scale to adjust the volume of the noiseto a comfortable and easily audible level. Additionally, the type ofsound may be selected between NBN (narrowband noise) at tinnitus pitchor BBN (broadband noise). By way of example, NBN at tinnitus pitchsupplies more gain without peak-clipping, especially in the case ofsteeply-sloping, high-frequency hearing loss. A peak clip indicator 183is provided if the adjusted volume via the slider scale is likely tointroduce peak-clipping. A halt button 184 is provided to halt theinterface. The OK button 185 may be operated to store the user-adjustedvolume setting in a data file, which may then be used by subsequentinterfaces.

Referring to FIG. 6, in one embodiment of the method a tinnitus soundmatching assessment may be performed using a first tinnitus sound-matchfunction interface 190 of the tinnitus diagnosis system. The purpose ofthis interface is to allow a patient to characterise their subjectivetinnitus percept via a sound library to help identify a tinnitussound-match from environmental sounds. The audiologist or clinician mayask the patient to describe their tinnitus and then proceed to play anysuitably matching sounds to the patient for their feedback on matching.It will be appreciated that the interface itself may alternatively beconfigured to guide the patient through this process automatically as aself-assessment tool if desired. A main sound library panel is providedat 191 comprising sound category tabs 192, and for each category one ormore sound buttons 193 that are operable to playback a sound of the typeindicated on the button for the patient's feedback for matching to theirtinnitus. A volume/intensity presentation level slider scale 194 isprovided for adjusting the presentation volume of the test sounds. Thedefault volume level is automatically set according to the audiometricthreshold values obtained by the audiometer interface 150. The volumelevel may be adjusted to be softer or louder using the scale 194depending on the patient's subjective tinnitus impressions. An equaliserbutton 195 may be operated to adjust the sound frequency components ofthe test sounds to improve sound quality if needed. The sound file pathin the sound library of the selected sound button may be displayed tothe user at 196. The sound library of different types of sound files maybe located locally in data storage on the host computer system or anaccessible external storage database. The closest environmental soundmatch may then be recorded for the patient or stored in a data fileassociated with the patient.

Referring to FIGS. 7-9, in one embodiment of the method a tinnitus soundmatching assessment may be performed using a second tinnitus sound-matchfunction interface 200 of the tinnitus diagnosis system. This secondinterface 200 may be used as an alternative to the first interface 190if the patient requires a larger sound library of environmental soundsfrom which to assess a tinnitus sound match. In this embodiment, theinterface 200 has three main sub-interfaces, namely a find soundinterface 203, a format sound interface 204, and a sound playerinterface 205.

Referring to FIG. 7, the find sound sub-interface 203 offers a searchinterface for searching the Internet for environmental sounds forplayback. A website search interface may be loaded by entering a websiteaddress into the URL bar 206. The website may be loaded into searchpanel 207 upon operation of the load button 208. The website address mayfor example be a sound search interface for searching the internet, anintranet or other database for sound files that match one or moredescriptive keywords and/or sound file parameters or a sound generationwebsite. The sound files located may then be played to the patient tofind the closest match to their tinnitus. The closest tinnitus-soundmatch files may also then be downloaded and stored from the sound filelinks.

Referring to FIG. 8, the format sound sub-interface 204 is configured toconvert any downloaded sound file from the find sound sub-interface 203as selected in the file path interface 212 into a suitable format foruse in the tinnitus diagnosis system. For example, the format soundsub-interface may be configured to convert a sound file into monoaural,16-bit with a 44100 sampling rate, or any other desired sound format andstore the formatted sound file. Success 213 and error 214 indicators areprovided to indicate whether the selected file has been successfullyformatted or not. A ramp button 215 is also operable to apply a rampfunction to the sound files to remove any audible pops, clicks ordistortion, if necessary.

Referring to FIG. 9, the sound player sub-interface 205 is configured asan audio tool for playing back a preview of the sound found via the findsound sub-interface 203, and which the patient perceives ascharacterising or describing their tinnitus percept. The sound file tobe previewed may be selected using the file selection panel 216 and thesound may be played to the patient or user by operation of the soundstart button 217. A volume adjustment is available via operation ofslider scale 218 to make the presentation softer or louder. Theinterface is configured to initially default to a presentation levelthat corresponds to the threshold values assessed in the audiometerinterface 205. An operable equaliser button 219 is also provided foradjusting the sound frequency components to improve sound quality, ifneeded. A stop button 220 is provided to halt playback.

Generation of Tinnitus Synthetic Sound

Reverting to FIG. 2, after one or more of the assessments 62,14 havebeen conducted, whether via the tinnitus diagnosis system interfaces orotherwise, the clinician generates a tinnitus synthetic sound 15 thatmost closely matches at least one, but preferably all, sound attributesof the tinnitus as perceived by the patient based on the informationobtained during the assessments. If the tinnitus diagnosis system isused, all the assessment information from the interfaces may be storedin one or more accessible data files associated with the patient andwhich profile the characterisation of their tinnitus. For example, thesynthetic sound 15 generated may be a tone, noise, or environmentalsound that is further signal processed to match the patient'scharacterisation of their tinnitus in terms of bandwidth, temporalproperties, loudness (intensity), and pitch, or any other assessed soundattributes. This synthetic sound 15 may be utilised as the test sound inthe next tinnitus spatial information assessment step 16.

Tinnitus Location

The next step 16 involves the clinician assessing the spatialinformation corresponding to the tinnitus as perceived by the patient.In this embodiment, the clinician determines the 3D direction vector in3D auditory space from which the tinnitus sound appears to originate asperceived by the patient. In this embodiment, the 3D direction vector isrepresented angularly by azimuth angle θ_(A) and elevation angle θ_(E)relative to a reference point or frame. It will be appreciated that thespatial information relating to the perceived tinnitus sound sourcedirection or location may be represented in any other suitable form ofcoordinate system if desired. In addition, it will be appreciated thatthe spatial information may comprise a 3D direction vector and magnitudeto the perceived sound source location so that distance as well asdirection to the location can be used when generating the spatialmasking sound.

Referring to FIG. 10A, an example of the 3D direction vector 106 toperceived tinnitus source location 100 is shown. In this example, thereference point 102 represents the centre of a patient's head and thecircular reference plane 104 is located parallel to the transverse planeof the human anatomy i.e. it extends horizontally from the back of thehead to the front of the head when upright. In one form, the referencepoint may be the center of the midline axis between the patient's leftand right ears. The 3D direction vector 106 to the perceived tinnitussource location is represented by azimuth angle θ_(A) representing theazimuth angle of the 3D direction vector 106 relative to referencevector 108 in the circular reference plane 104 and elevation angle θ_(E)representing the angular elevation of the 3D direction vector 106relative to the circular reference plane 104, which may be above orbelow the plane between 90 and −90°. The azimuth angle θ_(A) may beanywhere between 0-359°.

As will be explained in more detail later, the sound generation systememploys virtual acoustic technology to generate the test sound to appearto originate from a direction in 3D auditory space that corresponds tothe azimuth and elevation desired.

In one embodiment, the sound generation system is configured tosequentially generate a series of spatial sounds that are presented tooriginate through an azimuth angle of between 0-359° (elevationangle=0°) in the circular reference plane 104 in order to match to thetinnitus azimuth. As the series of test sounds (for example the tinnitussynthetic sound 30) are sequentially played through the azimuth range,feedback is received from the patient as to the test sound that mostclosely corresponds to the spatial location or direction from whichtheir tinnitus is perceived as originating from. Once the tinnitusazimuth is located, spatial sounds at that specific azimuth arepresented to originate through an elevation range of between −90° to90°, and feedback is received from the patient as to the elevation anglethat most closely corresponds to the tinnitus source location as theyperceive it. In one form, the test sounds may be swept continuouslythrough the azimuth and elevation ranges. In another form, the testsounds may be sequentially presented at discrete equi-spaced azimuth andelevation angles in the ranges or alternatively at non-uniformly spacedazimuth and elevation angles in the ranges as desired.

It will be appreciated that other testing processes may alternatively beused to assess the tinnitus azimuth and elevation angles. For example,the elevation angle may be assessed prior to the azimuth angle ifdesired. A further alternative may involve presenting the test soundsthrough azimuth and elevation angle ranges concurrently, i.e. presentthe elevation range at each azimuth angle or vice versa. In addition todetecting the direction of the perceived tinnitus sound source, theintensity of the test sounds may be varied so as to enable assessment ofthe perceived distance of the tinnitus sound source location relative tothe reference point.

In another embodiment, the sound generation system may be operable andcontrollable by the clinician or patient to manually vary the 3D spatiallocation (azimuth and elevation) of the test sound as desired to find alocation match. By way of example only, the sound generation system mayform part of the tinnitus diagnosis system. Referring to FIG. 11, a 3Dspatial location interface function 250 of the tinnitus diagnosis systemmay be operable to present a test sound to the user such that it appearsto originate from a desired 3D spatial location. The test sound file forplayback at the desired location may be selected using file selectionpanel 251. The sound file may be the synthetic sound file generated atstep 15 or any other desired test sound. The user may select the pinnasize of the listener, for example normal pinna or large pinna usingselection options 251,252 and this will configure the system to moreaccurately locate the test sound in virtual 3D space for the user usingvirtual acoustic technology. A diffuse field button 253 may be operatedto clean the sound signal, depending on the type of test sound that hasbeen selected. Operation of the start sound button 254 initiatesplayback of the test sound to the patient.

The interface 250 is configured to provide a display grid 258 thatrepresents the spatial location 255 of the test sound presented in areference frame relative to the center of the patient's head as shown atC. The Cartesian coordinates of the spatial location of the test soundare displayed at 256, and the elevation and azimuth displayed ininterface 257. The clinician or patient may drag and drop the cursor 255around the display grid of the GUI to alter the spatial location of thetest sound presented so as to find the closest match to the tinnituslocation as perceived by the patient. Each time the cursor is placed ina new position the spatial playback properties of the test sound arealtered to correspond to the new location. In this embodiment, thedisplay grid 258 represents the azimuth of the test sound location andthe user may configure this first by locating the cursor 255 at aposition on the grid that represents whether they perceive theirtinnitus to be originating. By way of example, the top of the grid mayrepresent the front of the head, the bottom of the grid the back of thehead, and the left and right sides of the grid may represent the leftand right sides of the head respectively. Once the azimuth of theperceived tinnitus location is determined, the user may then find theelevation of the perceived tinnitus location relative to the midlineaxis between their ears, i.e. whether the patient perceives theirtinnitus to be originating in a plane located at the midline (0°elevation) or plane above or below the midline. To adjust the elevation,the user may use the slide scale 259 to adjust the elevation of the testsound presented. Once the user has located the test sound in a positionthat most closely matches their perceived tinnitus location, they maysave this spatial information into a data file by operating the savebutton 260. A halt button 261 is also provided for halting the interfaceif desired.

The perceived tinnitus source location does not necessarily have to berepresented in 3D auditory space by azimuth and elevation anglesrelative to a reference point. In another forms, the 3D auditory spacemay be represented by three-axis Cartesian coordinates (X, Y, Z) asshown in FIGS. 10B and 10C. For example, the origin of the 3-axisorthogonal reference frame may again be the center of the midline axisbetween the patient's ears and this midline axis may be the X-axis. TheY-axis is orthogonal to the X-axis and extends horizontally between thefront and back of head, as shown in the display grid 258 of the 3Dspatial location interface function 250 for example. The Z-axis isorthogonal to the X-Y plane and extends vertically between the top andbottom of the head. Based on this reference frame, the patient'sperceived tinnitus location, such as a 3D direction vector, may bedefined by 3-axis X,Y,Z coordinates. The X, Y, Z axes may extendexternal to the patient's head.

Tinnitus Intensity at 3D Location

Reverting to FIG. 2, the next stage 17 is evaluating one or moreintensity levels for the test sound as perceived by the patient at thespatial location determined in the location assessment 16. The followinglevels may be determined: the threshold level (THL) at which the soundat the perceived tinnitus location can be detected, the minimum amountof intensity required for this sound to mask or cover the patient'stinnitus percept (MML—minimum masking level), and the amount ofintensity perceived to be as loud as the patient's subjective tinnituspercept (LVL). Sensation level methods may be employed to determine theMML. Residual inhibition tests for determining the occurrence, followingthe presentation of a masking sound, of temporary (partial or complete)suppression of an individual's tinnitus may be carried out. Loudnessgrowth and discomfort tests may be carried out in the form of astandardised measurement of loudness perception.

Referring to FIG. 12, in one embodiment, the tinnitus diagnosis systemprovides a tinnitus intensity assessment interface 270 that may beoperated by a user to determine one or more of the intensity levels MML,THL, and LVL. The interface 270 is operable to present a test sound,such as the generated synthetic sound 15 or otherwise, at the spatiallocation corresponding to the patient's perceived tinnitus at variousintensities for assessing the thresholds. The test sound file may beselected at file selection interface 271. The type of test or assessmentbeing conducted, for example MML, THL or LVL, may be selected in panel272. Playback of the sound file is initiated via the interface and maybe repeated for a number of desired iterations as selected at 273 withthe playback time remaining being displayed at 274. During playback, theuser may adjust the volume slider scale 275 to adjust the intensitylevel to suit the level being assessed, i.e. MML, THL, LVL. Once thevolume has been adjusted for each test level, the results or intensitylevel information are saved to a data file as triggered by operation ofthe save button 276. A halt button 277 is also provided to halt theinterface at any point if desired.

Set Personalised Masking Sound Parameters

Once the tinnitus diagnosis stage 12 is complete, the sound attributesinformation, spatial information, and intensity level informationrelating to the tinnitus as perceived by the patient is used as inputfor the next step of setting the personalised masking sound parameters18. As previously indicated, the assessment information may be stored inan accessible electronic data file or files, or recorded in any othersuitable form. Firstly, a new masking sound may be created or a previousstored masking sound selected at step 36 for loading into the remainderof the process. If a previous masking sound is selected, then the soundparameters of that sound will be personalized for the patient in view ofthe information from the tinnitus diagnosis stage. If a new maskingsound is to be created, then a stimulus will need to be selected from amasking sound library and the sound parameters of that stimuluspersonalised in view of the information from the tinnitus diagnosisstage. This library may include for example, but is not limited to,white noises, low frequency noises, fractal sounds, pseudo-randomvarying frequency tones (e.g. piano tones and the note), natural sounds(e.g. rain) or any other suitable therapy sounds. Alternatively, thetinnitus synthetic sound 15 generated in the tinnitus diagnosis stage 12can be loaded for the next masking parameter setting stage 18.

The next step 38 in personalisation of the masking sound is locating thespatial position of the 3D spatial masking sound by selecting targetazimuth and elevation angles. These angles are configured to correspondor match the tinnitus azimuth and elevation angles of the spatialinformation as assessed in the tinnitus diagnosis step.

The next steps 42 comprise modifying the selected stimulus of the newmasking sound or the pre-stored masking sound by tuning various soundattribute parameters, such as the bandwidth, temporal property,loudness, and pitch. In some embodiments, one or more of the soundattributes may be tuned so as to substantially correspond to one more ofthe corresponding parameters of the perceived tinnitus as determined inthe diagnosis step 12. As to loudness tuning, this can also be used tomatch the Minimum Masking Level (MML), Minimum Effective Masking Level(MEML) and Desired Masking Level (DML) of the spatial masking sound atthe virtual 3D sound source location for the individual patient, andwhich may be assessed in the calibration phase 62. MML represents theminimum level of sound required to cover the tinnitus making itinaudible. MEML represents the minimum level of sound that the listenerfinds effective in reducing tinnitus audibility. DML represents thelevel of sound the listener prefers to use to mask their tinnitus.

Set Additional Sound Processing Parameters

After personalisation of the masking sound has been configured,additional optional sound processing parameters 20 may be configured.These steps may be optional depending on the spatial masking sounddesired and the tinnitus treatment plan being employed by the patient.By way of example only, the play time 60 for the masking sound file maybe set and the diffuse-field 46 for the spatial masking sound may beconfigured to match a desired profile. For example, the diffuse-fieldmay be configured such that the flow of sound energy is substantiallyequal in all directions from the virtual 3D tinnitus source location oralternatively the diffuse-field may be configured to focus the soundenergy in one or more particular directions or regions.

Optionally, the intensity of the masking sound may be modulatedaccording to a ramping profile. For example, a ramp parameter or profile48 may be set and applied to the masking sound in order to vary theintensity or loudness of the sound over time in accordance with apredetermined profile. FIG. 13A shows a possible periodic rampingarchitecture with configurable parameters that may be applied to themasking sound to vary its intensity/volume during playback. As shown,the ramping profile may comprise a series of periodically repeatinguniform ramps (only two shown at R1, R2). The ramps initiate with agradual gain 280 relative to the un-ramped original signal level 281having a rise time period indicated at 282 such that the rate ofincrease may be adjusted. At the end of the initial gain, the ramp maythen be maintained at the upper level 283 for a steady state periodindicated at 284 until undertaking a gradual drop in gain back to theun-ramped original signal level 281 as shown at 285 over a fall timeperiod 286 such that the rate of decrease may be adjusted. The overallduration of the ramp is adjustable and shown at 287. The interval timeperiod 288 between the ramps is also adjustable, and there may be nointerval in some ramping profiles such that the ramping modulation ofthe volume of the masking sound is continuous.

It will be appreciated that all the parameters of the ramping profileoutlined above may be adjusted to generate a desired ramping profile toapply to the masking sound to modulate its intensity. By way of exampleonly, FIG. 13B one possible example of a ramping profile is shown in theform of a saw-tooth profile that may be applied to the masking sound toalter its intensity level over time. As shown, the ramping profile has asaw tooth pattern comprising a series of alternating gradual incrementsand rapid decrements in intensity level. In the saw-tooth profile, thereis no interval between the successive ramps. The intensity rise time 290is long and gradual, and is followed by an intensity drop time 291 thatis shorter and abrupt. In this example, there is no steady state period284 between the intensity increase and decrease periods. The alternatinggradual increments and rapid decrements in intensity enhance andmaintain a person's attention to sound over time, and this assists thepatient to attend to the masking sound in favour of their tinnitus. Theramping profile maintains attention by modulating the sound as asequence of stimulus ramps, where intensity increases are small andincremental, but stimulus decreases are large and abrupt. It will beappreciated that alternative intensity profiles or patterns may beapplied. For example, the pattern may alternatively be in an arc-type asopposed to saw-tooth, or any other periodic or repeating rampingprofile.

Generation of Spatial Masking Sound

The next stage 22 after the configuration of the sound processingparameters comprises generating the customised 3D spatial masking sound54 using audio processing systems (including, for example, onboard audioprocessing systems in hearing aids and/or headphones) and/or software inaccordance with the parameters set in the personalisation step 18 andsound processing step 20. In one embodiment, the synthetic tinnitussound 15 (which has one or more of its sound attributes matching thecorresponding perceived sound attributes of the patient's tinnitus) hasits spatial playback properties altered using virtual acoustic soundlocalisation algorithms and techniques such that it appears to originatefrom the patient's perceived tinnitus source location during playbackover left and right ear-level audio delivery devices. The playback time,diffuse field and any ramping profile are also configured for themasking sound in accordance with the configuration parameters. It willalso be appreciated that the 3D spatial making sound 54 generated may beany stimulus sound that is signal processed and modified in accordancewith the parameters set in steps 18 and 20. A test playback 56 of thegenerated masking sound 54 may be played for monitoring with headphonesvia a programmable attenuator and headphones buffer. If the playbackresults are favourable at decision point 58, the spatial masking soundis compiled into a digital or electronic sound file 64 or other soundrecording for storage on a suitable medium that can be accessed andplayed by a sound delivery system. In some embodiments, the 3D spatialmasking sound is represented in the form of stereo left and right earaudio signals for playback over left and right ear-level audio deliverydevices. If the playback results are not favourable, the personalisationand sound processing parameters may be reconfigured as desired, and themasking sound regenerated.

The virtual acoustic technology and examples of hardware systems forgeneration and/or playback of the spatial masking sound will now bedescribed in more detail.

3. Virtual Acoustic Processing Technology—Sound Localisation

The virtual acoustic technology employed in the tinnitus locationdiagnosis step 16 and the spatial masking sound generating process step54 employs the use of sound localisation techniques. Various techniquesfor altering the perceived location of sound in 3D auditory space areknown including using any one or more of the following, in combinationor alone, Interaural Time Difference (ITD), Interaural Level Differences(ILD), and Head-Related Transfer Functions (HRTFs). ITD and ILD tend tobe used to vary the perceived lateral location of the sound along themidline axis between a person's ears, but HRTFs enable sound to belocalised outside of the head and at any desired elevation.

The use of HRTFs is known in audio and sound technology field forcreating virtual acoustic spaces. HRTFs describe how a given sound wave(parameterised as frequency and source location) is filtered by thediffraction and reflection properties of the head, pinna, and torso,before the sound reaches the transduction machinery of the ear drum andinner ear. In brief, the HRTF defines how the head and outer ears filterincoming sounds. As is known to those skilled in sound technology, theHRTFs can be measured by placing miniature probe microphones into thepatient's ears and recording a bank of impulse responses to broad-bandsounds presented to the subject from a range of directions in space.

The impulse responses are sampled in time and a bank of associated HRTFsmay be formulated by Fourier transform of the impulse responses. Thereare two head-related transfer functions, HRTF_L, HRTF_R (one for theleft ear and one for the right ear) for each sound direction tested. TheHRTFs describe the phase and magnitude response at each ear as afunction of frequency, relative to the sound that would received at thecentre of the head in the absence of the listener.

The bank of HRTFs for the various sound locations may then be used togenerate sounds in specific locations in virtual 3D acoustic space. Aspatial sound signal, for example a binaural or stereo audio signal,appearing to originate from a virtual sound source location in 3Dauditory space can be created from a monophonic source signal byfiltering or convolving that monaural signal with the inverse of theleft and right ear HRTFs associated with the desired virtual location.Playing back the binaural audio signals directly into the ears, forexample via headphones, creates the illusion of the sound originatingfrom the virtual sound source location.

HRTFs vary from individual to individual and therefore the use of acustomised bank of HRTFs measured from the individual patient isbeneficial. However, average or ideal HRTFs are known and can beutilised instead of customised HRTFs.

Referring to FIG. 14, an example of the virtual acoustic technologyhardware setup is shown. The input sound signal, such a monaural signal300 may have any desired ramp profile applied by a ramp module 301 viamodulation with a ramping signal 302, although this is optional. Theramped signal is then filtered through left and right ear impulseresponses obtained from the inverse Fourier transforms of the left andright ear HRTFs for the determined tinnitus sound source direction(azimuth and elevation). In other words, the ramped digital input signalis convolved with the inverse Fourier transform of the left and rightear HRTFs at 304 a and 304 b. The left and right signals may then befiltered through diffuse-field equalisers 306 a, 306 b and attenuators308 a and 308 b if desired. The diffuse field equalisers 306 a,306 b maybe configured based on the parameters set in 46. The diffuse-field maybe configured such that the flow of sound energy is substantially equalin all directions from the virtual 3D tinnitus source location oralternatively the diffuse-field may be configured to focus the soundenergy in one or more particular directions or regions. The attenuators308 a,308 b may be configured based on the audiometer assessmentinformation obtained during the calibration 62. The resulting left 310 aand right 310 b output signals are then played to the patient via stereoaudio devices, such as binaural hearing aids, headphones or earphones orthe like.

4. An Example Embodiment of the Hardware Implementation of the TinnitusTreatment System

Various sound delivery systems and devices may be employed to deliver orpresent the 3D spatial masking sound to the patient. Some possibleexamples of systems and devices for carrying out this function will nowbe described by way of example only with reference to FIGS. 15a -20.

4.1 Tinnitus Treatment System Using Hearing Aid Devices

Onboard Sound Storage and/or Generation

In one embodiment, the sound delivery system for presenting the spatialmasking sound to the patient may comprise left and right hearing aidsdriven by a common external audio controller and which have onboardcircuitry for storing and/or generating the spatial masking sound.

Referring to FIG. 15a , a first form of hearing aid circuit 400 isshown. In this tinnitus treatment system similar left and right hearingaid circuits are employed although only one is shown for clarity. Eachhearing aid circuit comprises a stimuli storage module 402 that isarranged to receive and store the spatial masking sound file, forexample uploaded to the hearing aid from an external device such as apersonal computer 404 or the like. The hearing aid circuit includes acontrol unit 406 that communicates with an external remote audio controldevice 408. In this form of the system, the control unit 406communicates with the remote control device 408 wirelessly althoughhardwired connectivity could alternatively be used.

In operation, there is a user interface in the form of a single remotecontroller 408 which simultaneously communicates with both the left andright hearing aid circuits. The patient may operate the remotecontroller to initiate playback of the spatial masking sound by sendinga trigger signal 410 to each respective control unit. On receiving thistrigger signal 410, the control unit 406 is arranged to send a triggersignal 412 to the stimuli storage module 402 that contains the maskingsound file and to initiate playback. In this form of the system, thestimuli storage module 402 for the left hearing aid circuit retains theleft channel audio signal of the stereo spatial masking sound and thestimuli storage module of the right hearing aid circuit retains theright channel audio signal.

In this embodiment, a ramp unit or module 416 in each hearing aidcircuit is configurable to apply a ramping profile to the spatialmasking sound signal via a ramping signal 417 to modulate the intensityor loudness of the playback in accordance with a desired rampingprofile, as previously explained. It will be appreciated that the rampunit 416 may be deactivated if no ramping modulation is to be applied.

In their respective circuits, the left and right audio signals 414 afterbeing multiplied by any desired ramping signal 417 are received by thehearing aid processor 420 of the circuit where they are buffered andamplified, and transmitted to the hearing aid speaker 422 for playbackof the audio sound into the patient's left and right ears respectively.

The left and right hearing aid circuits are synchronised such that theplayback of their respective left and right audio signals, representingthe spatial masking sound, creates playback of the masking sound so asto appear to originate from a virtual sound source location thatsubstantially corresponds to the tinnitus source sound location asperceived by the patient.

Referring to FIG. 15b , a second form of hearing aid circuit that may beemployed in a tinnitus treatment system comprising left and righthearing aids synchronously controlled by a remote controller is shown.In contrast to the first form hearing circuit that stores the respectiveleft and right audio signals of the spatial masking sound onboard forplayback, the second form hearing aid circuit 500 comprises an onboardsound processor, such as a 3D synthesiser 502, that is arranged togenerate the left and right audio signals in real-time for delivering tothe patient.

As with the first preferred form of hearing aid circuit, a single remotecontroller 504 is arranged to communicate with each of the left andright hearing aid circuit and control the synchronised generation of theleft and right audio signals representing the spatial masking sound. Forexample, the remote controller is arranged to send trigger signals 510,via wireless or wired connection, to the 3D synthesiser circuits 502 ofeach respective hearing aid circuit. In response to this trigger, anoise generator 508 generates a monaural masking sound 506 that is thensubjected to sound processing to create the spatial and other soundattribute properties required of the masking sound when ultimatelydelivered by the left and right hearing aid circuit.

By way of example, the monaural sound signal generated by the noisegenerator 506 may be selected from a range of stimuli, including whitenoise, music, tones, background noise, sound effects or the like. On theinitiation of the monaural sound signal generation, a simultaneoustrigger signal 512 is sent to initiate ramp 519 and HRTF 516 signalsthat are arranged to modify the monaural signal 506. In particular, aramp module 518 generates the ramp signal 519 that modulates themonaural signal 506 in accordance with a desired ramping profile. TheHRTF module 520 for each circuit is arranged to generate an HRTF impulseresponse signal 516 that is convolved with the ramped monaural signal soas to generate the spatial property for the respective left and rightaudio signals such that when delivered to the patient they combine topresent a masking sound that appears to originate from a virtual soundsource location substantially corresponding to the 3D spatial locationas perceived by the patient. As before, the ramp module 518 may bedeactivated if no ramping of the masking sound is required.

The modified left and right signals 522 (from each of the left and righthearing aid circuits) then together represent the spatial masking sound.The hearing aid processor 524 of each circuit is again used to amplifyand buffer the respective modified left and right signals for sending tothe speaker 526 of each hearing aid so as to deliver the sound to thepatient. In an alternative form, the 3D synthesizer may be implementedor incorporated in the hearing aid processor 524

FIG. 16 shows the hardware devices of the tinnitus treatment system thatmay be employed to implement either forms of the hearing aid circuitsdescribed with reference to FIGS. 15A and 15B. By way of example, left610 a and right 610 b hearing aids for a patient to wear are shown. Theplayback of the spatial masking signal via the hearing aids iscontrolled synchronously by an external remote controller 600 that sendsthe hearing aids respective control signals 612 a, 612 b wirelessly, forexample using Near Field Magnetic Induction (NFMI), Bluetooth, FM,infrared, or any other wireless transmission. The remote controller mayalternatively be hardwired via cable(s) to the hearing aids if desired.

External Sound Storage and/or Generation

In another embodiment, the sound delivery system for presenting thespatial masking sound to the patient may comprise conventional left andright hearing aids driven by a common external audio control device thatis arranged to store, generate, and/or send the left and right audiosignals representing the spatial masking sound to the hearing aids forplayback.

Referring to FIG. 17, this embodiment of the tinnitus treatment systemcomprises an external audio control device 700 that is arranged to sendleft and right audio signals to respective left and right hearing aidcircuits 702 (only one shown for clarity) for playback. In one form, theaudio control device 702 may comprise a storage memory module 704 forstoring the spatial masking sound and/or stimuli sounds for generatingthe spatial masking sound. Such stimuli sounds may include sounds thatare configured to match one or more of the patient's perceived tinnitussound attributes. A sound processor module 706, such as a 3Dsynthesiser, is provided for generating the left and right audio signalsrepresenting the spatial masking sound using virtual acoustic spaceprocessing in real-time of the stimuli sounds from memory 704. The 3Dsynthesiser may operate in a similar manner to that described withreference to the 3D synthesiser of FIG. 15b by altering the spatialproperties of the stimuli sounds to create a virtual sound sourcelocation that corresponds to that of the perceived tinnitus sourcelocation. The sound processor module 706 may be provided in the form ofa programmable hardware device, such as a Digital Signal Processor (DSP)or any other programmable microprocessor. In addition to implementing a3D synthesizer function to generate the real-time spatial masking sound,the sound processor module may also be arranged as an audio player. Theaudio player may be provided with a user interface that is operable tocontrol delivery (e.g. playback) of the masking sound, such as start,stop and pause functions, and other typical audio parameters such asvolume.

The audio player of the sound processor module 706 can be configured tocontrol generation of the masking sound by the 3D synthesizer andpresentation/delivery of the sound to the audio delivery devices, and/orcan be configured to load and control playback of masking sound audiofiles that have been preloaded or stored in storage memory module 704 orwhich are received via the input/output port 708 explained below. Inother embodiments, the sound processor module 706 need not necessarilyinclude a 3D synthesizer for generating masking sounds and could bearranged only as an audio player that controls playback of storedmasking sound files in memory 704 or received from the input/output port708.

An input/output port 708 is provided for receiving sound files and forcontrolling the sound processing parameters and configurations togenerate the desired spatial masking sound for playback. A userinterface may also be provided for controlling the generation andplayback of the spatial masking sound. The user interface may beintegrated with the audio control device 700 or an external device thatcommunicates with the control device via the input/output port 708. Theuser interface may be provided in the form of any suitable electronicuser interface, including, but not limited to, buttons, dials, switches,touch-screen or any combination thereof. An input/output transmissionmodule 710 is provided to enable wireless or wired connectivity andcommunication with each of the left and right hearing aid devices.

When playback of the spatial masking sound is initiated by a useroperating the audio control device 700, the left and right audio signals711 generated by the 3D synthesiser and/or provided from the storagemodule 704 are simultaneously and synchronously sent to the respectiveaudio input modules 712 of the respective hearing aid circuits (ifhardwired to the audio control device) or to the respective wirelessreceiver modules 714 if wireless communication is employed. The audiosignals 711 are then received and processed by their respective hearingaid processors 716, for example they may be buffered and amplified, andthen sent to the respective left and right hearing aid speakers 718 forplayback to the user.

FIGS. 18 and 19 show a range of various hardware devices that may beemployed to implement the tinnitus treatment system of FIG. 17. Asmentioned the system comprises left and right audio delivery devices inthe form of left and right hearing aids that are controlled by an audiocontrol device or devices 802. The audio control device may be providedin various forms with varying capabilities. For example, in some formsthe audio control device may simply store, transmit and control playbackof the spatial masking sound, but in other forms the audio controldevice may have sound processing capabilities such that it is alsooperable to generate and modify the spatial masking sound. It will alsobe appreciated that these functions may be spread over multipleinterconnected or communicating devices.

In one form 804, the masking sound is stored on a remote device 806 thattransmits and controls playback over the hearing aid devices 800.

In another form 808, the audio control device may comprise any suitablegeneric sound or audio player or device having such functionality, suchas a Personal Computer 810, portable audio player 812, PDA 814 or thelike, that is arranged to generate, store and/or control playback of thespatial masking sound. The audio player may send the left and rightaudio signals representing the spatial masking sound directly to thehearing aids 816 or indirectly via other intermediate transmission orcontrol devices. For example, such intermediate control devices maycomprise a remote control device 818 or wireless transmission device820. It will be appreciated that connection and communication betweenthe audio player and any intermediate control devices may be wirelessly,for example using NFMI, Bluetooth, FM, infrared or any other wirelesscommunication protocol, or via wired cables, or a combination of thetwo.

In another form 830, the audio control device 820 may be in the form awireless transmission device that is arranged to store, transmit andcontrol playback of the spatial masking sound via wireless communicationwith the hearing aids 800. In this form, the spatial masking signal maybe uploaded onto the audio control device 820 in the form of a digitalsound file for playback via an onboard audio player that can process thesound file and generate the audio signals for transmission to thehearing aid devices 800.

4.2 Tinnitus Treatment System Using Headphones

In another embodiment shown in FIG. 20, the sound delivery system maycomprise audio delivery devices in the form of standard left and rightheadphones 900, ear buds or earphones that are worn by the user and fromwhich the left and right audio signals representing the spatial maskingsound is played.

It will be appreciated that the audio signals may be transmitted to theheadphones 900 from any suitable audio control device that is capable ofstoring, generating and/or controlling playback of the spatial maskingsound. For example, the audio control device 902 may be in the form of aPersonal Computer, portable audio player, PDA, cell phone or any othersuitable device. Wireless headphones may alternatively be used and inwhich case a wireless transmission device 906 integrated or external tothe audio control device 904 may be employed to transmit the audiosignals to the headphones for playback.

4.3 Tinnitus Treatment System—Integrated or Standalone Sound DeliverySystem

In other embodiments, the sound delivery system may comprise left andright audio delivery devices that are integrated with one or moreonboard audio control devices rather than having an external audiocontrol device. The onboard audio control device may store the maskingsound file for playback or generate the masking sound in real-time, andis operable via a user interface to control synchronised playback of theleft and right audio signals over their respective left and right audiodelivery devices to generate the audible spatial masking sound for thepatient. In one form, the sound delivery system may be a standalonetreatment system. In another form the sound delivery system may beintegrated into another device or expand the functionality of anotherdevice. For example, the sound delivery system may be integrated intotwin left and right hearing aid system with onboard audio control forthe spatial masking sound playback. The left and right hearing aids maycommunicate wirelessly to coordinate synchronised playback of the leftand right audio signals representing the spatial masking sound.

In summary various sound delivery system embodiments are possible andthe audio control device may be completely or partially integrated withthe audio delivery devices or entirely separate and external.

The foregoing description of the invention includes preferred formsthereof. Modifications may be made thereto without departing from thescope of the invention as defined by the accompanying claims.

1. A system for determining a spatial property of tinnitus as perceivedby a person comprising: a sound generation system that is operable topresent test sounds to the person from a range of virtual sound sourcelocations in 3D auditory space; and a feedback system that is arrangedto receive person feedback indicative of the virtual sound sourcelocation that most closely corresponds to the spatial location in 3Dauditory space of the source of the tinnitus as perceived by the personand output spatial information indicative of the spatial location of thesource of the tinnitus based on the person's feedback.
 2. A systemaccording to claim 1, wherein the sound generation system is configuredto sequentially present test sound to the person from a range ofdifferent virtual sound source locations.
 3. A system according to claim1, wherein the sound generation system is user operable to present thetest sounds from user selected virtual sound source locations.
 4. Asystem according to claim 1, wherein the test sound has one or moresound attributes that substantially correspond or match one or more ofthe perceived sound attributes of the person's tinnitus.
 5. A systemaccording to claim 4, wherein the sound attributes comprise any one ormore of the following: pitch, frequency, bandwidth, temporal properties,intensity, loudness, and sound type.
 6. A system according to claim 1,wherein the sound generation system is configured to present the testsound to the person sequentially at different azimuth and elevationangles within respective predetermined azimuth and elevation rangesrelative to a reference point in a 3D auditory space reference frame. 7.A system according to claim 6, wherein the reference point is the centreof the midline axis between the ears.
 8. A system according to claim 6,wherein the sound generation system is configured to present the testsounds by continuously sweeping through the entire azimuth and elevationranges.
 9. A system according to claim 6, wherein the sound generationsystem is configured to present the test sounds sequentially at a seriesof discrete azimuth and elevation angles.
 10. A system according toclaim 1, comprising a graphical user interface.
 11. A system accordingto claim 1, wherein the system is operable by the person.
 12. A methodof determining a spatial property of tinnitus as perceived by a personcomprising the steps of: sequentially presenting test sounds to theperson from a series of virtual sound source locations in 3D auditoryspace; and receiving feedback from the person as to virtual sound sourcelocation that most closely corresponds to the spatial location in 3Dauditory space of the source of the tinnitus as perceived by the person.